Difficult problems in biology have always stimulated developments in analytical chemistry, and advances in analytical sciences have allowed us to ask more sophisticated questions in biology. Mass spectrometry and its evolving applications to nonvolatile biomolecules provide clear examples of this synergy. In the post-genomic era, the next big questions are being answered by the science of proteomics—the analysis of the proteins produced by cells. Although this new area has been enabled primarily by mass spectrometry, its rapid and robust development world-wide has stimulated major advances in multi-stage HPLC, 2D gel electrophoresis, mass spectrometry and protein-based bioinformatics.